hi guys im new to this site and was wondering if you guys could help. i own a se4 cefiro which is a 4wd 20det cefiro and iv had a rb25det out of a stagea put in. it runs fine the only problem is that the 4wd dosnt work anymore . iv checked the codes on the attesa ecu and it giving me the code 21 which is a tps problem please help!!!